I. Field
The following description relates generally to wireless communications, and more particularly to Physical Random Access Channel (PRACH) transmission in an environment having multiple carriers.
II. Background
Wireless communication systems are widely deployed to provide various types of communication; for instance, voice and/or data can be provided via such wireless communication systems. A typical wireless communication system, or network, can provide multiple users access to one or more shared resources (e.g., bandwidth, transmit power, . . . ). For instance, a system can use a variety of multiple access techniques such as Frequency Division Multiplexing (FDM), Time Division Multiplexing (TDM), Code Division Multiplexing (CDM), Orthogonal Frequency Division Multiplexing (OFDM), and others.
Generally, wireless multiple-access communication systems can simultaneously support communication for multiple mobile devices. Each mobile device can communicate with one or more base stations via transmissions on forward and reverse links. The forward link (or downlink) refers to the communication link from base stations to mobile devices, and the reverse link (or uplink) refers to the communication link from mobile devices to base stations.
Wireless communication systems oftentimes employ one or more base stations that provide a coverage area. A typical base station can transmit multiple data streams for broadcast, multicast and/or unicast services, wherein a data stream may be a stream of data that can be of independent reception interest to a mobile device. A mobile device within the coverage area of such base station can be employed to receive one, more than one, or all the data streams carried by the composite stream. Likewise, a mobile device can transmit data to the base station or another mobile device.
Within a multiple carrier wireless environment, there are numerous uplink and/or downlink carriers that are within such heterogeneous networks. Access procedure involves a user equipment (UE) obtaining C-RNTI, establishing uplink (UL) synchronization, receiving physical channel configurations and/or obtaining information for RRC connected mode. Moreover, a Physical Random Access Channel (PRACH) process involves the UE to initiate a PRACH message to a base station via an uplink carrier, wherein the base station replies via a downlink carrier. However, in a multiple carrier environment, multiple downlink carriers can be associated with one uplink carrier.